- Heterotopic pancreas is a relatively common congenital anomaly, usually found incidentally during laparotomies. The jejunum is an uncommon site; stomach and duodenum are the most frequent reported locations. Every pathologic change that occurs in the pancreas can occur in its heterotopic counterpart, but neoplastic transformation is rare. Most reported cases of neoplastic transformation are ductal adenocarcinomas, and there are only a few reported cases of mucinous neoplasms arising in heterotopic pancreas. We report a mucinous neoplasm arising in a heterotopic pancreatic tissue in the jejunum of an 86-year-old woman found during a laparotomy for bowel ischemia. Because of the presence of focal papillary architecture and cytologic atypia, the tumor was classified as a borderline neoplasm. To the best of our knowledge, is the first reported case of a borderline mucinous neoplasm occurring in heterotopic pancreatic tissue.